The invention relates to a mirror supporting structure for a monochromator, particularly to a mirror supporting structure for a monochromator suitably applicable to an optical spectrum analyzer.
In a monochromator used for an optical spectrum analyzer, a mirror is installed for irradiating light toward spectro-elements such as diffraction grating. To correct a light path of reflected light by a mirror, a mirror supporting structure for a monochromator is provided with an angle adjusting means for finely adjusting the attaching angles of the mirror.
Such a conventional mirror supporting structure 40 for a monochromator is described hereinafter with reference to the attached drawings. FIG. 6 is a view showing a conventional mirror supporting structure 40 for a monochromator, FIG. 7(A) is a plan view of FIG. 6 and FIG. 7(B) is a side view of FIG. 6. As shown in FIG. 6 and FIGS. 7(A), 7(B), the mirror supporting structure 40 for a monochromator comprises a plate-like base 41, a mirror holding block 42 mounted on the base 41 and a mirror 43 fixed to the mirror holding block 42. The mirror holding block 42 is fixed to the base 41 via bolts 52 and the mirror 43 is fixed to a mirror bonding face of the mirror holding block 42 by an adhesive and the like. The mirror supporting structure 40 for a monochromator having such a construction has angle adjusting means 45 provided in the mirror holding block 42.
The angle adjusting means 45 comprises a slit 44 which is formed in the mirror holding block 42 and is parallel with the plane direction of the base 41, a slit upper wall part 42a and a slit lower wall part 42b which are respectively disposed on the mirror holding block 42 so as to sandwich the slit 44 therebetween, slit opening screws 61a, 61b and slit closing screws 61c, 61d. 
The slit opening screws 61a, 61b are threaded into screw holes provided on the slit upper wall part 42a, and tip ends thereof are brought into contact with the slit lower wall part 42b. When the slit opening screws 61a, 61b are turned so as to be fastened, the tip ends thereof push the slit lower wall part 42b to open the slit 44. As a result, the mirror 43 is turned about the innermost part 44aof the slit 44 clockwise in FIG. 7(B).
Meanwhile, the slit closing screws 61c, 61d are inserted into the insertion holes provided in the slit upper wall part 42a, and the tip ends are threaded into the holes provided on the slit lower wall part 42b. When the slit closing screws 61c, 61d are turned so as to be fastened, the heads thereof push the slit upper wall part 42a to close the slit 44 so that the mirror 43 is turned about the innermost part 44aof the slit 44 counterclockwise in FIG. 7(B).
With the angle adjusting means 45 having the foregoing construction, when the slit 44 is opened or closed, the mirror holding block 42 is deformed so that the mirror 43 supported by the mirror holding block 42 is inclined so that the angle of the mirror can be adjusted by turning the mirror 43 about the innermost part 44aof the slit 44.
However, the conventional mirror supporting structure 40 for a monochromator has the angle adjusting means 45 alone as means for adjusting the angle of the mirror 43, and the mirror supporting structure 40 can turn the mirror 43 only about the axis line in one direction. Accordingly, there has been required a mirror supporting structure for a monochromator which can turn the mirrors about the axis line in one direction and also in an axis line crossing this axis line in other direction, namely, can turn the mirrors in two directions.
The invention has been made to satisfy the foregoing requirement and it is an object of the invention to provide a mirror supporting structure for a monochromator capable of turning mirrors for the monochromator about axis lines which cross each other when the attachment angles of the mirrors of the monochromator are adjusted, thereby turning the mirrors for monochromator to adjust the attachment angles of the mirrors in two directions.
The mirror supporting structure for a monochromator of a first aspect of the invention is characterized in comprising first angle adjusting means for turning mirrors about a first axis line which does not cross each plane direction of the mirrors at right angles, and second angle adjusting means for turning the mirrors about a second axis line which does not cross each plane direction of the mirrors at right angles but is parallel with a line crossing the first axis line.
For the first angle adjusting means and the second angle adjusting means, a conventional structure or a structure having a bearing, a shaft and the like may be employed. Further, the first axis line of the first angle adjusting means and the second axis line of the second angle adjusting means may cross each other at right angles or may cross each other at a given angle.
The crossing at right angles or the crossing means a case where the first axis line of the first angle adjusting means and the second axis line of the second angle adjusting means are arranged in parallel with imaginary lines which cross each other at right angles or cross each other at a given angle as well as a case where the first axis line of the first angle adjusting means and the second axis line of the second angle adjusting means directly cross each other. With the mirror supporting structure for a monochromator having the foregoing construction, since the first and second angle adjusting means are provided and the first axis line of the first angle adjusting means and the second axis line of the second angle adjusting means cross each other, the attachment angles of the mirrors can be adjusted in two directions, thereby obtaining the foregoing object.
Further, the mirror supporting structure for a monochromator of the second aspect of the invention is characterized in that the first angle adjusting means of the first aspect of the invention comprises a first leg member and a second leg member which are spaced from each other, and a support member installed between the first and second leg members for supporting the mirrors, wherein the mirrors are supported in a manner that each plane direction of the mirrors do not cross the installing direction of the support member and the support member can be turned about a line which is parallel with the installing direction thereof.
For the support member, e.g. a plate-like or a bar member can be exemplified, and a structure for holding the mirrors via block-shaped mirror support member and the like can be employed. The support member may have folded parts at both ends, i.e. may be formed of substantially a U-shape, and it may have a structure to be turned about the first leg member and the second leg member via respective folded parts.
With the mirror supporting structure for a monochromator of the second aspect of the invention, since the mirrors are supported by the support member installed between the first and second leg members, the mirrors constituting the monochromator can be reliably attached, and the attachment angles of the mirrors can be freely adjusted.
With the mirror supporting structure for a monochromator of the second aspect of the invention, if the support member is formed substantially in U-shape, the first axis line of the first angle adjusting means and the second axis line of the second angle adjusting means can be disposed relatively to approach to each other, thereby minimizing the movement of the mirrors involved in the adjustment of the attachment angles.
The mirror supporting structure for a monochromator according to the third aspect of the invention is characterized in that multiple mirrors are attached to the support member. Respective mirrors may be disposed in substantially plane symmetry while sandwiching the plane which crosses the installing direction of the support member at right angles or may be disposed in the same direction. With such an arrangement, the multiple mirrors can be adjusted in their attachment angles, for example, they can be effectively applied to a single path type monochromator wherein incident light passes through diffraction grating one time, and also to a multi-path type monochromator wherein incident light passes the diffraction grating two times.
The mirror supporting structure for a monochromator according to the fourth aspect of the invention is characterized in that the first angle adjusting means is arranged such that one end of the support member in the installing direction of the support member is connected to the first leg member via a bearing while the other end of the support member in the installing direction of the support member is connected to the second leg member via a cylinder member, and wherein an axis line of the bearing and an axis line of the cylinder member are aligned with the same line which is parallel with the installing direction of the support member.
Since one end of the support member in the installing direction and the first leg member are connected to each other via the bearing, while the other end of the support member and the second leg member are connected to each other via the cylinder member, it is possible to provide a protrusion on the other end of the support member, and the second leg member may be fixed to the protrusion so as to engage therein, for example, by aligning the cylinder member with the axis line of the bearing, while the protrusion is engaged in the hole of the cylinder member so as to align the axis line of the cylinder member with that of the bearing so as to form a single axis line (first axis line), so that the support member can be installed between the first and second leg members without generating distortion in the support member. Further, the thus installed support member can be more smoothly turned about the first axis line which is in parallel with the installing direction by use of the bearings so as to adjust the attachment angles of the mirrors.
The mirror supporting structure for a monochromator according to the fifth aspect of the invention is characterized in that the second angle adjusting means has holding blocks supported by the support member for holding the mirrors, slits which are formed in the holding blocks and are continuous along a plane substantially parallel with the installing direction of the support member and sandwiched between a pair of walls, slit opening screws and slit closing screws penetrating one of walls in a direction of the thickness of the walls, and wherein the slit opening screws are threaded into one of walls, and tip ends of the slit opening screws are brought into contact with the other of the walls, and wherein the slit closing screws are inserted into one of the walls, and tip ends of the slit closing screws are threaded into the other of the walls.
With such a second angle adjusting means, for example, when the slit opening screws which are threaded into the slit upper walls of the slits are fastened, the tip ends thereof press the slit lower walls so that the slits are opened, and hence the mirrors are turned about the uppermost part (second axis line) of the slit.
Meanwhile, when the slit closing screws which are inserted into slit upper walls and threaded into slit lower walls are fastened, the heads thereof press the upper slit walls so that the slits are closed, and hence the mirrors are turned about the uppermost part (second axis line) of the slits (in a direction opposite to a case where the slit opening screws are fastened).
With such a second angle adjusting means, when the slits are opened or closed, the holding blocks are deformed, and the mirrors held by the holding blocks are inclined so that the attachment angles of the mirrors can be adjusted to a direction crossing the first axis line of the first angle adjusting means at right angles or a given angle.
The mirror supporting structure for a monochromator according to the sixth aspect of the invention is characterized in that both the first and second axis lines are parallel with pair of lines which cross each other at right angles. As a result, when the attachment angles of the mirrors of the monochromator are adjusted, such attachment angles of the mirrors can be adjusted in two directions which cross each other, thereby the mirrors can be easily disposed in desired three-dimensional directions.